As image forming apparatuses such as a printer, facsimile, copier and multifunctional machine including functions of printer, facsimile and copier, an ink-jet recording medium, an inkjet recording apparatus is known. The inkjet recording apparatus, for example, utilizes a recording head or an image forming mechanism equipped with a liquid droplet ejecting head for forcing ink droplets of recording liquid (hereinafter referred to as ink droplets) out to adhere the ink droplets to a sheet while conveying the sheet. Thereby, image formation is carried out. The sheet herein not only refers to paper, but also refers to a recording medium, a transfer material, a recording sheet and the like. The image formation herein refers to recording, printing and imaging.
In a case where an image is formed by an inkjet recording method, the ink is adhered to the sheet. Consequently, the moisture contained in the ink causes the sheet to deform. This phenomenon is referred to as cockling. Due to cockling, the sheet may ripple so that the position of a nozzle of the recording head and the sheet surface varies from place to place. In a case where the level of cockling is high, in a worst case, the sheet touches the nozzle surface of the head, thereby contaminating the nozzle surface of the head and the sheet itself. As a result, the image quality deteriorates, and a misalignment of the ink droplet landing position may occur due to an effect of cockling.
In view of the above, in a related art inkjet recording apparatus, according to Japanese Patent Laid-Open Application Publication No. JP2004-175494, for example, an endless charging belt to maintain the flatness of the sheet is provided. The charging belt surface is charged so as to electrostatically suction the sheet. By forcing the charging belt to circulate in this state and to convey the sheet, the sheet is prevented from separating from the charging belt. Accordingly, high flatness is maintained.
According to Japanese Patent Laid-Open Application Publication No. JP2000-246981, since cockling and curling of printing sheet affect printing image, in a printing sheet conveyance apparatus for carrying out a printing operation in which printing sheet is electrostatically suctioned by an electrostatic suction member at a printing position to print on the printing sheet and for moving printing sheet, a mechanism for switching, depending on a type of printing sheet used, between a state where the printing sheet is suctioned by the electrostatic suction member and a state where the printing sheet is not suctioned by the electrostatic suction member is proposed.
Furthermore, in Japanese Patent Laid-Open Application Publication No. JP2000-246981, a mechanism for causing a cleaning mechanism to touch or not to touch the image receiving surface of the electrostatic suction member is provided. During the process of printing at the time of continuous printing sheet feeding, cleaning is carried out on the image receiving surface of the electrostatic suction member by the cleaning mechanism.
As described above, in the electrostatic conveyance apparatus for suction of a sheet-type material such as paper to the conveyance belt by electrostatic suction force in order to convey the sheet, when the conveyance belt is charged by the charging mechanism, charged products are generated on the surface of the conveyance belt. Consequently, there is a concern that suction may be reduced, as the number of conveying sheet increases.
In this case, however, as described in Japanese Patent Laid-Open Application Publication No. JP2000-246981, it is not adequate enough to recover the reduction of suction caused by the charged products, when foreign substances such as paper dust adhered to the surface of the conveyance belt is removed by the cleaning mechanism. Furthermore, there is a concern that while the cleaning mechanism removes the foreign substances charging the conveyance belt, the charged compounds may be generated.